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It’s an obvious statement to say successful farm management decisions need both agronomic and economic considerations. Farmers weigh out input cost versus the benefit to yield and quality of grain before making the decisions to buy and use new or additional products.

Agronomy and economic crop management goes much beyond inputs. Consideration of crop rotation, Cost of Production, seeding date and weather indicators for disease all need to be considered. Within agronomic decisions there can be tools to estimate the economic impacts of different decisions. The ‘My Farm’, ‘Cost of Production’, ‘Canola Reseed Calculator’ and ‘Sclerotinia Treatment Decision Tool’ are all based on yield trends and agronomy to help make economic decisions easier.

Every year disease surveys occur, not only Manitoba, but across Canada and other countries around the world. So why conduct these surveys? Disease surveys are an important component of integrated disease management plans. The surveys can give an indication of potential problems if disease levels are high, if there are changes in pathogen types or races occurring, supply information that can be used in the future for monitoring and control measures, and provide historical information on the occurrence and severity of disease in Manitoba and the assessment of losses from disease.

The CANADIAN PHYTOPATHOLOGICAL SOCIETY (CPS) publishes their annual CANADIAN PLANT DISEASE SURVEY, available on the website at http://phytopath.ca/publication/cpds/. It is a periodical of information and record on the occurrence and severity of plant diseases in Canada and the estimated losses from diseases. For Manitoba, historical information is provided for various diseases and crop types, such as in cereals Fusarium Head Blight, smut, stem rust, leaf rust, stripe rust, crown rust, and in canola sclerotinia stem rot, blackleg, aster yellows and clubroot. Information for other crop types are also available, including field beans, flax, peas, soybeans, corn and sunflowers.

Biosecurity. Surveys also play a role in crop biosecurity and plant health. An important part of minimizing or preventing the spread of pests is early detection through timely scouting, monitoring, assessment and decision-making. A strong information network that is often created through surveys and its reporting provides for resources in assessing new problems and alerting others about potential risks.

So if you are a producer and someone asks if they can include your field in an annual disease survey, consider saying yes!

There are a number of great resources and articles by experts in other areas of Canada and the United States. Here are two articles by Andrew Friskop, Extension Plant Pathologist with North Dakota State University, on the factors producers should consider when evaluating an early-season fungicide application in wheat (i.e. herbicide timing or T1).

There are several factors that will influence the value of an early-season fungicide and Andrew Friskop reviews some of those, including crop rotation, tillage, weather, variety selection, scouting & fungicide selection. The 2016 article reads “What to expect from an early-season fungicide application? – Studies conducted by NDSU over the last 20 years have shown that a 2 to 6 bushel response occurs when an early-season fungicide was used in a wheat-on-wheat production system with minimum tillage when favorable weather was present. The incorporation of other management tools such as crop rotation and tillage will reduce the risk of tan spot development and reduce the expectant yield response. Also, remember an early-season fungicide will protect the leaves available at the time of application, but as the wheat crop matures, newly developed leaves will be left vulnerable to leaf spot and rust pathogens.”

One factor not discussed in the articles was disease resistance management – it must be another consideration. When a fungicide is used multiple times, the risk that pathogens can develop resistance to the fungicide can increase. Where fungicide application is required, producers should rotate between fungicide groups.

Stripe rust, also known as yellow rust, is caused by the fungus Puccinia striiformis and can affect wheat, barley and triticale. Stripe rust is identified by small, yellowish uredinia that appear in linear rows the length of the leaf blade (see figure).

Stripe Rust in Winter Wheat (Photo by P.de Rocquigny, 2015)

In Manitoba, stripe rust does not overwinter. Instead, the majority of our stripe rust inoculum blows in from the central US states by what is known as the “Puccinia Pathway”. Normally the first inoculum starts arriving at the beginning of June. However, this can vary depending on how much inoculum is present in the United States and when the winds blow from the south.

Fortunately, the progress of stripe rust inoculum, as well as other cereal rusts, is documented on the USDA’s website (http://www.ars.usda.gov/News/docs.htm?docid=9757). To date, there have been a number of stripe rust detections in winter wheat, with the most recent located in North Dakota (in winter wheat research plots in two different counties – as reported by Andrew Friskop, Cereal Extension Pathologist with NDSU Department of Plant Pathology).

In Manitoba, majority of winter wheat is in the stem elongation stage of development. There have been no reports of stripe rust to date; however, inoculum can move quickly so growers should scout their winter wheat for early infections. The good news is stripe rust can be managed by timely fungicide applications. If the disease pressure, weather conditions (stripe rust favours cool, damp conditions) and crop yield potential warrant application, foliar fungicides should be applied before the disease is well-established in the crop to provide maximum benefit. There are numerous products available for the control of stripe rust; please refer to the Guide to Field Crop Protection.

For the first time in 2015, FHB risk maps are available in both Saskatchewan and Manitoba. At a glance, on a given day the maps may appear to indicate a different risk for growers in each province, which can be concerning for farms along the Manitoba-Saskatchewan border. However, closer examination will reveal minor differences in the models and maps useful for considering FHB risk.

In Saskatchewan, maps are created with models (depending on spring or winter wheat) using temperature and/or relative humidity in the previous 5 days, plus 2 days forecast. While in Manitoba, maps are created with a model that uses the hours of precipitation and the hours with temperatures between 15°C and 30°C during the previous 7 days. Each province then has its own categorization based on slightly different threshold values – low, moderate, high (and extreme in Manitoba) – based on the output from their respective models.

Models are also constantly validated and fine-tuned for the region where it is relevant. The model that is best for the Fusarium population and conditions in individual provinces in western Canada, or even across the border in the USA, might not be the same. However, crop scientists and pathologists continue to work together to determine how FHB risk maps can be most valuable to all farmers, including those along the border! Producers along the border may have a potential advantage in assessing risk, by using both maps and interpreting which one is most relevant for their farm. And keep in mind risk maps may not perfectly represent a producer’s individual field(s).

Regardless of the model used, no FHB risk map can be taken as a stand-alone tool to make management decisions about FHB as it only takes into account environment. The existence of disease requires 3 factors: the interaction of a susceptible host, a virulent pathogen, and an environment favourable for disease development. So although a risk map in Saskatchewan or Manitoba may show High risk due to environment, disease risk may be low if the wheat crop is not at the proper stage for infection.

We strongly encourage referring to additional information and consultation with local extension specialists and agrologists to determine if fungicide applications are needed to suppress FHB in your area.

If you have any questions on the FHB Risk maps or FHB management, please contact Manitoba Agriculture or the Saskatchewan Ministry of Agriculture.

The changes over the past week signal to producers to continually scout their fields for local conditions as their crop progresses. But remember the disease triangle – the existence of a disease requires three factors: the interaction of a susceptible host, a virulent pathogen, and an environment favorable for disease development. Therefore, although the most current risk map shows high risk levels due to environment in some areas of the province, disease is prevented if the winter/spring wheat is not at the proper stage for infection.

Reduction of pest movement in crops, is good business for everyone involved. Though producers are responsible for their operations, others working on agricultural lands have also have the responsibility to reduce pest movement, introduction or increase of pest populations (ex: weed, insect, disease, nematode, etc.), as these all can have long-term negative effects on farm productivity.

Submitted by John Gavloski, MAFRD Entomologist and Holly Derksen, MAFRD Field Crop Pathologist

Aster leafhoppers and other species of leafhoppers have been observed in large numbers in an individual winter wheat field in east-central North Dakota (NDSU Crop & Pest Report, May 14) At this time, aster leafhoppers have not been reported in Manitoba, and it is too early to know what the risk is for crops in Manitoba. Determining the risk will involve knowing when they arrive in Manitoba, what the populations are like, and what percent of the population carries the aster yellows phytoplasm. But it is not too early to start scouting for them in vegetation that is tall enough to sweep with a sweep net. Aster leafhoppers are small, about 2-3 mm long as adults, wedge-shaped, and have six distinctive dark coloured spots on their head (see image). Adults will readily fly when disturbed.

Aster leafhoppers can carry aster yellows, a disease caused by a bacterium-like organism known as a phytoplasma. Aster yellows can infect many crops including carrot, potato, flax, and cereals. Although canola is not a preferred host plant, aster leafhoppers will feed on it, and signs of aster yellows are quite visible in canola. Aster yellows was a significant problem for canola growers (and potentially cereal growers) in 2012. The leafhoppers blew in early and often in 2012 and had high levels of infectivity with aster yellows. The earlier a plant becomes infected with this disease, the more significant the yield effect can be. It is unknown at this time what percentage, if any, of the leafhopper population currently present in North Dakota is infected with aster yellows.

There are no economic thresholds for aster leafhopper in field crops. They are highly mobile insects that move quickly from crop to crop and new populations can blow in from the south at any time of the year.

Stripe rust has been reported in winter wheat fields in Alberta this spring (http://www.producer.com/2015/04/stripe-rust-in-alberta-winter-wheat/). This could indicate that the fungus overwintered on the crop. Overwintering of stripe rust in Canada also occurred in 2011, a year where there were measurable losses from stripe rust in both winter and spring wheat in Alberta and parts of Saskatchewan. That year a breakdown in resistance in the 2010 planted winter wheat crop led to higher infections leading into 2011. Persistent snow cover allowed for good overwintering conditions and a cool, wet spring favoured spread and infection of the stripe rust fungus. Growers in Alberta are being encouraged to vigilantly scout for the spread and proliferation of this disease this spring, especially in varieties that do not carry any resistance. Reports from Montana and Oregon have also indicated an early outbreak of stripe rust with fungicide applications being recommended in many cases.

In Manitoba, the majority of our inoculum blows in from the central US states by what is known as the “Puccinia Pathway”. Progress of this inoculum, as well as other cereal rusts, is documented on the USDA’s website (http://www.ars.usda.gov/News/docs.htm?docid=9757). To date, there have been a number of stripe rust detections with the furthest north located near Omaha, Nebraska. There have been no reports of stripe rust in Manitoba, however, inoculum can move quickly so growers should continue to scout their winter wheat and newly emerging spring wheat for early infections. The ideal timing for a fungicide application for protection against stripe rust in wheat is at the flag leaf stage. If rust infections are only noticed later in the year, especially past the flowering stage, a fungicide is likely unwarranted as the yield effect will be minimal.

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Reference material

Diseases: New clubroot cases have been confirmed in the Rural Municipalities of Lorne and Dufferin. Insects: Scouting for bertha armyworm continues with some reports of insecticide applications. Spider mites being noticed in some soybean fields. Grasshopper populations are variable. For full report see Insect & Disease Report – August 1, 2018

Crops are advancing rapidly with the warm and dry conditions. Rain is needed in most areas to sustain crops and replenish soil moisture. Harvested has started in winter cereals, barley, and peas. Swathing or pre-harvest applications have started in early seeded spring cereals and canola. Fist cut hay is nearing completion; yields are below normal. […]

Diseases: The second case of clubroot in canola this year has been reported. Disease surveys in soybean and wheat are ongoing and disease levels are low overall. Insects: Overall insect concerns in field crops are relatively low. There are still some areas where grasshopper levels are being watched. Spider mite levels are being monitored in some soybean fields in […]

Disease – Goss’s wilt was observed near St. Claude. Insects – Grasshopper populations are being monitored in and around the edges of some fields. Armyworms have been noticed in some cereal fields in the Central and Eastern regions. No soybean aphids have been reported yet. For more details and information see http://www.gov.mb.ca/agriculture/crops/seasonal-reports/manitoba-insect-and-disease-update-2018-07-11.html

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Favourable weather and field conditions have allowed seeding operations to begin, with a provincial estimate of <5% of the 2017 crop seeded. For the full crop report, see on-line at http://www.gov.mb.ca/agriculture/crops/seasonal-reports/crop-report-archive/crop-report-2017-05-01.html

The Guide to Crop Protection provides information on the use of herbicides, fungicides and insecticides for control of weeds, plant diseases and insects. This publication is only a guide. Always refer to the product label for application details and precautions. It is available: online at https://www.gov.mb.ca/agriculture/crops/guides-and-publications/#gfcp. Individual sections on Weed Control, Plant Disease Control and Insect […]

Did you know you can view the 2017 edition of Seed Manitoba, as well as past editions, on www.seedmb.ca? Well, you can! Flip-view digital editions of the current guide (2017), as well as the six most recent editions, are available at http://www.seedmb.ca/digital-edition/. Also, full PDF versions are available at http://www.seedmb.ca/digital-edition/pdf-editions-and-separate-section-pdfs/ where you can download the entire […]

http://www.gov.mb.ca/agriculture/crops/plant-diseases/clubroot-distribution-in-manitoba.html Map shows positive clubroot findings by Rural Municipality, discovered through laboratory testing for presence of clubroot spores in soil and/or positive confirmation of clubroot symptomatic plants. Testing was done from 2009-2014 and is still considered limited. Positive findings have been at low spore concentrations and sporadic throughout the province. As more fields are sampled, the map will be updated. As less than […]